I don't think a lot of people really understand why TV manufacturers are interested in Quantum Dots.
I'll give you a hint: LG's OLED technology utilizes color filters over white OLEDs. This is actually what is going on inside LCD TVs, the backlight is white and the liquid crystals have a color filter which blocks light except for red, green, and blue.
Neither approach can provide a wide enough color gamut to meet the requirements of Rec.2020, which is wider than even DCI P3 that is used to produce movies today. You can't just have a 10-bit LCD panel, you need a better way of managing color reproduction than color filters over a white backlight. You also can't just have an OLED panel with white OLEDs with color filters.
The only way to meet the requirements of Rec.2020 is to improve how the colors are produced. Samsung's RGB OLED technology could meet Rec.2020. LG's OLED technology as it exists today cannot, nor can any existing LCD technology.
Enter Quantum Dots. The QD overlay over the panel or the backlight assembly improves the ability to reproduce red, green, and blue over just straight up color filters over white light. With QD, it is possible for existing LCD panels today to meet Rec.2020. And yes, if LG chooses to use it in the OLED TVs, they will be able to meet Rec.2020 with their existing OLED technique which utilizes white OLEDs instead of RGB OLEDs.
Until Samsung re-enters the OLED market with their RGB OLED TV designs, QD technology will be required on all existing TV designs to meet Rec.2020.
As a side note, the people shitting on existing 4K LCD TVs for not being able to meet Rec.2020 are quite hilarious because they are ignoring the fact that all 4K OLEDs right now also cannot meet Rec.2020. OLED is the saviour of nothing here, if you're going to bash 4K LCD for just being "higher resolution 1080p panels" you'd better start including the existing 4K OLEDs in that categorization. They cannot meet Rec.2020 color gamut either. Neither can without QD.
If anybody cares to see exactly what Quantum Dots actually do, they can look at this:
http://www.avsforum.com/forum/166-l...in-lg-s-2015-uhdtv-lineup-4.html#post30057970
Someone actually measured the native color gamut of a TV with QD, the 2013 Sony X900A. Sony didn't bother with QD in 2014 on the X900B. You can see the difference in native color gamut in that diagram of the gamuts of those two TVs vs. Rec.709, DCI P3, and Rec.2020.
Both the X900A and X900B use 10-bit LCD panels. You can see that a 10-bit panel by itself isn't nearly enough for coverage of DCI P3 or Rec.2020. This is because color filters over white light just isn't good enough, you need to improve the quality of the light produced and ideally separate it into pure R, G, and B. LG's white OLEDs have exactly the same problem.
The Sony X900A had a somewhat wonky looking coverage of the color space, you can see that while it's noticeably wider than Rec.709 it manages to miss a portion of that gamut's green color space. Proper design and implementation of QD will be important to properly cover the intended color space, but even this first-generation QD design, were it better calibrated, would have been plenty wide enough to have covered DCI P3. A better QD implementation should have no issues fully covering DCI P3, it remains to be seen just how close to coverage of the extremely wide Rec.2020 color space QD technology can get.
Well, not everyone has been stating that
only LCD 4K is simply a 1080p panel at a higher res. OLED has likely slipped through the cracks in such references because as yet, there isn't a mainstream 4K OLED available worldwide. I for one have been very adamant that current 4K ... in general ... is just a higher res 1080p, and is missing the features that truly makes UHD a worthy upgrade.
What I did say about OLED however is that while full Rec 2020 has not been demonstrated, it can (including current LG) display a much wider gamut than Rec 709. So even if initially it doesn't handle full spec, there is an obvious improvement over conventional LCD.
That said, you seem confused on how the LG implementation works. If anything, it's very similar to QD already. The reason conventional LCD's have a small gamut is because of the crappiness of the light source. Using a traditional 'white' LED (which is actually a blue LED doped with a yellow coating), they simply cannot get the correct white color temperature. Enter quantum dots. A blue LED is used as a backlight, with a red and green QD layer in order to generate the needed white color temperature. Combined with a high quality color filter, they can generate a wide color gamut. Granted I haven't seen the research on where they're at now, so I can't say whether the full Rec 2020 is immediately tenable, but the point is we get a gamut far in excess of traditional TV.
For the LG OLED design, we actually have a very similar mechanism. As with traditional LED's, at this point we do not actually have a true white OLED in mass production. LG's 'white' OLED subpixels are actually created by layering red, green, and blue OLED's in order to generate white light. The resulting subpixels then have a color filter (red, green, blue, and clear) in order to create the final pixel. Assuming in the long run they can tune the OLED layers to generate the same frequencies of red, green, and blue as what a QD TV does, and then use the same high quality filter layer, there's no reason to assume they can't produce the same gamut. It's essentially the same mechanism.
One possible issue (and I can't confirm whether it is one) is the 4 subpixel layout they use - red, green, blue, white. Current OLED has issues with aging, and in order to lengthen the lifespan it behooves the manufacturers to keep the voltage down. LG's trick of using a white subpixel not only compensates for light loss from the color filtering process, but actually gives them headroom beyond. In order to generate the correct colors however, they need to map the traditional RGB values in a CLUT that incorporates RGBW. It's possible that color conversion may limit the gamut or create inaccuracies? I don't know.
The point it, even LG's design should be capable of competing or at least coming close to QD in terms of gamut. Or at worst, is still well in excess of current standards. It should be a visible improvement.
Right now though, they are still using 8-bit color depths though. So gradations is arguably the biggest hurdle they need to overcome in the short-term. Otherwise they're going to have obvious artifacts/crush once HDR content starts rolling in. Of course that also brings into question whether they can currently even run bright enough without premature aging? Granted that's a different argument.
